As part of our ongoing collaborative efforts in Structural Genomics we have identified a number of yeast gene products with no known structural homologue. One of the identified proteins, Pyridoxamine 5-phosphate oxidase, was expressed in E. coli, purified to homogeneity and crystallized. The initial characterization of very small crystals (~10 microns maximum dimension) at X9B showed that diffraction extends to at least 3.0E and is consistent with the hexagonal space group P3121 (or enantiomorph) (a=b=74.8, c=157.7E). The solution of this structure will particularly interesting as it promises to provide a non-conventional fold for a flavin containing protein, and is likely to represent a completely novel fold. Furthermore, this structure will be of great interest to the field of basic metabolic chemistry as this enzyme is responsible for the biosynthesis of vitamin b6 and pyridoxal-5-phosphate.